Source note · Call transfer semantics REFER and Replaces
On accepting a replacement a user agent shuts down the replaced dialog differently by its state: a confirmed dialog is accepted with a 2xx and ended with a BYE, an early dialog that the user agent itself initiated is accepted with a 2xx and ended with a CANCEL, and an early dialog that the user agent did not initiate is refused with 481 and left unchanged.
Checked 2026-09-16
- Vendor
- IETF
- Product
- Session Initiation Protocol
- Subsystem
- Replaces
- Deployment
- not restricted
- Region
- not restricted
- Release range
- Standards Track
- Checked
- 2026-09-16
Sources
- RFC 3891 — The Session Initiation Protocol (SIP) "Replaces" Header — IETF / RFC Editor · tier 1 standards and regulators · RFC 3891 section 3, the 3 dialog-state paragraphs following the authorisation rules
Cite this note
APA
WarmTransfer. (2026, September 16). Call transfer semantics REFER and Replaces: source note xfersem-replaces-bye-or-cancel-by-dialog-state. WarmTransfer. https://warmtransfer.net/knowledge/claims/xfersem-replaces-bye-or-cancel-by-dialog-state
BibTeX
@misc{warmtransfer-claim-xfersem-replaces-bye-or-cancel-by-dialog-state,
title = {Call transfer semantics REFER and Replaces: source note xfersem-replaces-bye-or-cancel-by-dialog-state},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/xfersem-replaces-bye-or-cancel-by-dialog-state},
note = {Source note xfersem-replaces-bye-or-cancel-by-dialog-state, checked 2026-09-16}
}